Electric-arc lamp.



WILLIAM a. mom, or nAkEwoon, oHio, nss 'onoit' r or CLEVELAND, 01110, A' CORPQgRAfIIOLT ELEcT irc-Anc LAMP.

Specification of Letters Patent.

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No Drawing. Original application filed June 6, 19 a, Seria1 lio,;7i2,l3 Q Divide an 'aagggpiiaaan;nag

September 28,1914.

To all whom it may concern Be it known that I, WILLIAM R. Morr, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Electric- Arc Lamps, of which the following is a 'full, clear, and exact description.

My invention relates to are light electrodes containing materials for producing a flaming or luminous arc, and is more particularly adapted to those of a carbonaceousnature.

This application is a division of my application Serial No.-=772,130, filed June 6, 1913.

One object of my invention isto use materials in an arc'lamp electrode. of the flaming type that will increase the candle power, and at the same time reduce oreliminate slagging on the positive electrode. which as a rule contains the flaming material.

Another object of my invention is to provide a material that can be used in the negative electrode to prevent slag formations thereon.

Another object of my invention is to provide the particles of the flaming material with a non-hygroscopic coating or incrusta tion to protect them from moisture.

Other objects will appear in the appended description. 1

Flaming arc electrodes consist of a body of carbon with flaming materials such as the fluorids of calcium, rare-earths, etc., and are supporting materials such as potassium and sodium salts. Most of the materials used with the carbon produce more or less slag. My invention is particularly adapted for use in solid electrodes having such a flaming mixture, though not necessarily limited thereto. .1

It is not new to use silica, silicates and such compounds of siliconas carborundum, etc., in lamp electrodes. However, thosilica used is obtained v-from. the natural crystalline product which has. very objectionable: .features. J 0.

In flaming electrodes, the natur'abfiorm of silica causes insulating buttons of; slgs-to form on the ends of electrodes whichob'so'ure tinguished, the lamp can not restart as-the insulating buttons-prevent the conducting can constituents of the le tr d 9 C n 14:15? -t; 51 I, I hei e; 9 i .ltl t chemically. precipitated ilica, wh n us d.- wi h flam g. m e i y he place of the natural crystalline silica, silicon, rundu iz o the sil cate of I .sqdipotassium and calcium, increases the candle power very,,consideralflyaandgrcduces the slagging .tendencies togsuchgan-, extent-.tha t they can be said to be; practically; eliminated, I canuot y beyond q e tion exactl why the precipitated form proliloesxsuch radi-j 6 cally difl'erent -resul;ts,-l )ut Lbelieveyit isi-on account of the extreme fineness of the parti: cles and the increasedchemicaLreaction-that takes place in the. arc,

e :2: v Certain types of flaming electrodes;.giye excellent results asiar aslightzefiiciency concerned, but on account of containingicelr tain calcium compoundsland carbonates, the baking in the furnace results in the-formaf tion of calcium oxid. Calcium oxid or lime 7 will absorb moisture from the air to pro duce calcium hydroxid and finally calcium carbonate, which frequently causes complete disintegration of the electrode. I; have known electrodes strong. and rigid in all respects to be reduced to powder in a short time after being stored-where the moisture of the air could reach them. I have found that this disintegration canbe practically eliminated by incorporating precipitated silica in the electrode containing carbonates and compounds of calcium.-

Silica could be prepared-in any. of. the ways well known to chemists, such as precipitating it from a solution of asilicate 90 with some acid such as nitric, sulfuric or hydrochloric. :The silica may also be prepared .by oxidizing silicon vapor by bringingit in contact with: the oxygen of the air.

zilheelectrode (in usual practice the positive :electrode-hmay? be" made upof carbon and; v a'rimistkindsof flaming'mater-ials with which: is incorporated; the precipitated silica. Thee'l'otter ha's'zits-admhtages(when used in any kind? ofm. carbonaceous flamingi mixture, 1 00 hi itzasi Ja -typical. 1 example -.of Tithe; :electrode composition, the. following ma be givent coke mor oth er "carbonaceous; material, 50% to.:60%; precipitated silica -L% ;to*6% and the remaind'en'of-flamin-g and are supporting 1 materials" such as rare-earth=ifiu orids,w calas bone compounds in com cium fluorid or other alkaline fluorids with borates, carbonates, tungstic oxids, etc. These materials may be homogeneously mixed with carbon to form a solid electrode, or they may be incorporated partly or en tirely in the core of the electrode.

In forming the oxids of tungsten and silicon, I find it advantageous to precipitate both simultaneously from a mixture of soluble silicates and tungstates by the addition of an acid as previously described. This gives a very intimate mixture of the two oxids which is a desirable feature.

In direct current flaming lamps of the carbonaceous type, the flaming material is mostly in the positive electrode, the negative electrode containing little or no materials that enhance the flaming property of the arc, except in that type of lamp in which the stub from the burned out positive electrode is placed in the negative holder to constitute the negative electrode. If an electrode is composed of various materials in such proportions as to reduce slagging when it acts as a positive electrode, it is liable to slag very badly when the stub is used as a negative electrode. In all cases, it is extremely diiiicult to prevent slag formations on a negative electrode, and as far as I am aware, there is no material or combination of materials so eflicient in eliminating slag on the negative electrode as the precipitated silica, constituting one of the objects of my invention. This material, when put in a negative electrode causes it to burn with a clean point, and very little trouble in slagging is experienced. My invention, therefore, is especially useful in those types of flaming lamps in which the positive stub is used as the ne ative, since the precipitated silica contained therein acts also to eliminate slag when it is used as the negative. In other words, my improved combination of materials tends to make a universal electrode for direct current lamps. Boric oxid, aluminum oxid and chromic oxid have somewhat the same efi'ect as the silica when used in negative electrodes, but in a much less degree.

Tungsten compounds, one of which has been previously mentioned, have been found to be a valuable constituent of lamp electrodes, as tun sten forms many complex compounds wit numerous other elements, and, inasmuch as the efficiency of the arc seems to depend upon the number of possible compounds that can be formed therein, it adds greatly to the efiiciency. However, on account 0 the comparatively hi h cost of tungsten, I have ex erimented wit other materials with the i ea of decreasing the amount of tungsten necessary, or eliminating it al ether. I have found that the tungstic oxid can be replaced by phosphoination with other materials such as the recipitated silica previously described. Tiie substitute materials produce substantially as good a light as the tungstic oxid, and at the same time eliminate the slag formations almost altogether.

I have obtained electrodes that burn with high candle power and substantially no slag by incorporating the phospho-boric compounds in combination with silica in a flaming mixture. The silica is preferably used in the form of a precipitate for the reasons previously given. After the silica is precipitated, it is placed in a solution of boric and. phosphoric acids and evaporated to dryness. I also prefer to heat the residue to a low red heat. This process causes a phospho-boric incrustation to be formed on the small articles of the silica which protect them rom moisture, since the phosphoboric compound is non-hygroscopic and insoluble. This is a very important feature as some substances produce an eflicient light but are hygroscopic to such an extent as to cause disintegration of the electrode, as previously explained.

The chemical composition of the coating on the silica particles has the formula B O,P,O, and in making the solution of the boric and hosphoric acids, it is preferable to mix t em in the approximate proportions to unite in the above form. As an example of an electrode composition containin these last mentioned materials, the following may be given, though the proportions can be cha-n ed without entirely eliminating the deslrable features produced thereby. Coke or other carbon, 55 parts; calcium or rare-earth fluorids, 32 parts; carbonates of sodium and potassium, 5 parts; silica and phospho-boric compound 6 parts. To this also may be added one part fused borax and one part barium sulfate.

The process can also be used to apply a coating or incrustation on materials other than silica. It is not new to use phosphoboric comlpounds in electrodes per se, but I believe am the first to use such material as a coat around the particles of another material to be incorporated in a lam electrode. I also lay claim to the broad idea of applying an incrustation to such particles and instead of usin phospho-boric compounds I may use ot or substances, sodium sulfate and potassium chlorid being given by way of example.

In my original application previously mentioned, of which this is a division, the claims relate to the use of precipitated silica in an arc lamp electrode and in another 00- pending divisional application, Serial No. 863,881, filed September 28, 1914, claims are drawn to the protecting coating.

Having described my invention, what I claim is:

1. In an arc lamp for direct current, a

positive electrode containing flaming materials in combination with a negative electerials in combination with a negative electrode containing particles of precipitatd trode containing precipitated silica. silica incrusted with a protecting coating of 2. In an arc lamp for direct current, a a hospho-boric compound. 5 positive electrode containing 'flaming man testimony whereof, I hereunto afiix my 15 terials in combination with a negative elecsignature. trode containing particles of precipitated WILLIAM R. MOTT. silica incrusted with a protecting coat. Witnesses: A 3. In an arc lamp for direct current, a Y P. P. BETHEA,

10 positive electrode containing flaming ma- H. G. GROVER. 

